Top feed mechanisms for blind stitch sewing machines



Dec. 18, 1934. c. w. MUELLER TOP FEED MECHANISMS FOR BLIND STITCH SEWING MACHINES Filed Jan. 22, 1954 III 3 MW, C/mzies Wflfzaeiler.

Patented Dec. 18, 1934 PATENT OFFICE TOP FEED MECHANISMS FOR BLIND STITCH SEWING MACHINES Charles W. Mueller, St. Louis, Mo., assignor to Lewis Invisible Stitch Machine Company, St. Louis, Mo., a corporation of Maine Application January 22, 1934, Serial No. 707,825

6 Claims.

This invention relates to new and useful improvements in sewing machines generally although more particularly to a top feed mechanism adapted for use in connection with blind stitch sewing machines of the single thread chain stitch type.

Heretofore, in blind stitch sewing machines of the type specified the top feed dog has been mounted on the front end of a lever which is mounted on a main frame of the machine for sliding pivotal movements and is actuated by an eccentric cooperating with the rear end of the lever. In this construction the fulcrum point for the lever is fixed and consequently the feed dog is given a 4-motion movement in which the up and down movement thereof is variable in proportion to the throw of the eccentric. The throw of the eccentric has heretofore been changed either by substituting V a different eccentric or by providing a radially adjustable eccentric. With this construction it has been found that when feed strokes are imparted to the feed dog the up and down movement of the feed dog is correspondingly diminished and consequently the feed dog would not clear the fabric especially if a heavy fabric is being stitched. It has also been found in feed mechanisms of this type that when the feed travel of the feed dog has been considerably increased the up and down movement to the feed dog will be correspondingly increased and this feed dog in its upward movement will be moved to such an extent as to interfere with the looper which cooperates with the needle in the usual way in forming the chain stitches.

The principal object of this invention is therefore to provide a fixed adjustable fulcrum for the feed lever whereby the up and down movement imparted to the feed dog will be constant regardless of the. length of travel imparted to said dog. I V 7 Another object of the invention is to provide an adjustable throw eccentric for actuating the feed lever and to provide indicating means for the eccentric and indicating means for the adjustable fulcrum of the feed lever whereby'the latter may be properly adjusted to correspond with the adjustment made to the eccentric.

With these and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawing.

In the drawing:- Figure 1 is a side elevation showing a top feed mechanism embodying the subject matter of my invention, and showing the. adjustable fulcrum for the lever in one extreme position of adjustment,

Figure 2 is a similar view but showing the fulcrum in its other extreme position of adjustment,

Figure 3 is a top plan view thereof, a part of the machine frame being shown in section to better disclose the mounting for the adjustable fulcrum of the feed bar lever,

Figure 4 is a detail vertical sectional view taken through Figure 1, and

Figure 5 is a perspective view of the adjustable fulcrum block.

Like reference numerals designate corresponding parts throughout the several figures of the drawing.

In the accompanying drawing, 5 designates a part of the main frame of a blind stitch sewing r;

machine and 6 the main shaft which is rotatably journaled therein. Disposed in front of the main shaft and rigidly attached to the main frame by any suitable means, not shown, is the usual presser foot? which is provided with a longitudinal feed slot 8. A feed dog 9 is located abovethe presser foot and is fixedly securedto the front end of a feed lever 10, and this feed dog is adapted to operate in the slot 8 to feed the fabric rearwardly. An adjustablethrow eccentric 11 is operatively connected to the rear end of the feed lever 10 in the usual manner and inasmuch as the construction of this eccentric is well known, it is thought unnecessary to specifically show or describe the same. The major axis of the feed lever 10 is disposed in a substantially horizontal plane. Formed in the face of the frame 5 adjacent the feed lever 10 is a horizontally disposed groove 12. Slidably mounted in this groove 12 is a fulcrum block 13 having a T-shaped opening. A clamping nut 19 is threadably engaged on the outer end of the bolt to clamp the block in any position of adjustment along the groove 12. The block 13 is provided with an upwardly extending flange 20 having a horizontal straight edge 21, and with a depending fingerpiece 22. A stud 23 is fixed to the block 13 and journaled on this pivoted stud is a fulcrum roller 24, the roller being held on the stud by a disc 25 which is of a diameter greater than the diameter of the roller. The fulcrum roller 24 is located in a transverse slot 26 which is formed in the feed lever 10 and extends longitudinally thereof, this slot being located intermediate the ends of the lever.

The adjustable throw eccentric 11 includes a,

rotatable sleeve 27 having a series of number designations 28 thereon, said designations being,

thereby vary not only the feed stroke of the feed dog but also the up and down movement thereof. Located on the exposedface of the flange 20 of the fulcrum block 13 is a series of number designations 29, said designations being indicated by the numerals 3, 4, 5' and 6 respectively. A pointer 30 is mounted on the main frame 5 for cooperation with said number designations 29.

In practice when the adjustable throw eccen tric 11 is adjusted for a given lengthof feed stroke, the fulcrum block 13 is properly adjusted so as to shift the fulcrum pin 23 and roller 24 longitudinally of the feed lever 10 and thereby position said fulcrum roller in corresponding relation to the adjustment made to the eccentric 11. The block is adjusted by first loosening the clamping bolt 16, then effecting the adjustment of the block in place by tightening the clamping nut 19.

From the foregoing, if a short stitch is desired the eccentric 11 will be set at the numeral 6 of the number designations 28 and the block 13 will beshifted toward the eccentric and set at the corresponding numeral 6: of the number designations 29. Consequently, although the length of the stitch has been. changed the up and down movement imparted to the feed dog has not changed. If a long stitch is desired, the eccentric 11 will beset at the numeral 3'and the block 13 will be adjusted to the number 3 as shown in Figure 1. Therefore, although the length of the stitch has been increased the up and down movement imparted to the feed dog has not been changed. V

It=wil1, therefore, be seen that I have provided a top feed dog including a feed lever and means for maintaining a uniform feed lift'to the feed dog regardless of the length of the forward travel of said dog, and consequently the feed dog will under all circumstances rise above and thereby clear the fabric and at the same time will not interfere with the looper which cooperates with the needle in forming a single thread chain stitch. H a g Itis of course to be understood that the details of structure and arrangements of parts may be variously changed and modified without departing from the spirit and scope of my invention. f

I claim:

1. 'A 4-motion top feed mechanism for sewing machines comprising in combination a feed lever, a feed dog connected to one end of said lever, a

sliding fulcrum for the lever, means connected to the other end of the lever for imparting up and down and back and forth movements to the feed dog, and means for mounting said fulcrum for fixed adjustments longitudinally along the lever to vary the up and down movements of the feed dog. V

2. A 4-motion top feed. mechanism forbsewing machines comprising in combination a feed lever, a feed dog connected to one end of said lever, a sliding fulcrum for the lever, means connected to'the other end of the lever for imparting up and down and back and forth movements .to the feed dog, and means for mounting said fulcrum for fixed adjustments longitudinally along the lever to vary the up and down movements of the feed dog, said mounting means in- "cluding a slidable block, and a fulcrum roller carried by. the block.

'3. A i-motion top feed mechanism for sewing machines comprising in combination a feed lever, a feed dog connected to one end of said lever, a sliding fulcrum for the lever,means including an adjustable eccentric connected to the other end of the lever for imparting up and down and back and forth movements to the feed dog, means for indicating the throw of the eccentric, means for mounting said fulcrum for fixed adjustments longitudinally along the lever to vary the up and down movements of the feed dog, and means for indicatingthe proper adjustment of the block to correspond adjustment of the eccentric.

4. A bmotion top feed mechanism for sewing machines comprising in combination a frame, a feed lever, a feed dog connected to one end of the lever, a fulcrum for the lever mounted on the frame for slidable adjustments longitudinally along the lever to vary the up and down movements of the feed dog, and means connected to the other end of the lever for imparting up and down and back and forth movements to the feed dog.

7 5. A e-motion top feed mechanism for sewing machines comprising in combination a frame, a a feed lever, a feed dog connected to one end of the lever, a block mounted on the frame for slidable adjustments along the lever, a fulcrum pin fixed to the block and having a sliding connection with the lever, means for clamping the block to the frame inan adjusted position of the former, and means connected to the other end of the lever for imparting up and down and back and forth movements to the feed dog.

6. A 4-motion top feed mechanism forsewing machines comprising in combination a frame, a feed lever, a feeddog connected to' one end of the lever, a fulcrum for the lever mounted. on the frame for slidable adjustments longitudinally along the lever to vary the up and down movements of the feed dog, means including'an adjustable eccentric connected to the. other end of the lever for imparting up and down and back and forth movements to the feed dog, means for with the indicating the throw of the eccentric, and means CHARLES w. MUELLER. 

